text: Most examples of Z-ligands are boron-centered molecules. These can range from the simple BX molecules such as BF, BH, BCl, and BR, to the more complex boron-centered molecules such as B(CF). In addition, there are many complex boron-centered molecules that act as multiple ligands on a single metal atom, forming "scaffolding" structures. One such structure is shown to the right. Other molecules that act as Z-ligands are AlCl, AlR, SO, H, Me, CPh, HgX, Cu, Ag+, CO and certain silanes.